I was thinking about this yesterday:
BA/KLM
Full Merger or very deep alliance.
Harmonise service across the two and market it as one product.
Route all 'bucket and spade' international transfer traffic through Schipol, all O&D premium as point-to-point from Heathrow / Gatwick / Manchester / Glasgow?
So, an airport such as BAH or DXB has 2 BA/KLM frequencies a day - one to LHR and one to AMS. Fiddle with Amadeus (or whatever it is these days) so that a passenger wanting a Premium seat BAH-JFK is routed via LHR and a passenger wanting an economy seat on the same route is sent via AMS. I.e. you're making those wanting to fly via and to Heathrow pay for the privelege.
Ditto to the European routes. Cities with high transfer traffic go to AMS, which is a better airport for that sort of thing anyway, and the premium people go to LHR.
The volatility of both the N. Atlantic markets and the Premium sector are such that an airline would have difficulty concentrating on them exclusively, and you must have a low-yield, volume backup which stays relatively static. After all, in a recession, it's the business passengers who stop flying first.